The present invention relates to generally microphones incorporating CMOS (complementary metal-oxide-semiconductor) and MEMS (microelectromechanical systems) technologies. A MEMS microphone generally includes a backplate formed within a silicon oxide layer and a membrane that moves above the backplate in response to acoustic pressures (i.e., sound). The backplate is formed by etching a cavity on the backside of the silicon wafer. According to this method, the thickness of the backplate is determined by the duration of the backside etching.